The
EPA Action
Level
for radon
gas in indoor air is 4 picocuries
per liter (pCi/L). The EPA would prefer that you start reducing your
exposure at 2
pCi/L.
That's
because people living in homes with 4 pCi/L could be receiving 300
to 800
millirem (mrem)
a year. In 2009, the NJDEP reported (pps.
19-20)
that the lifetime risk for lung cancer at this level is about 24 in
1000, which is equal to 24,000 in one million. They define lifetime
exposure as 30 years.
The average level of radon in homes in NJ, 2.4 pCi/L, has a lifetime risk of cancer of 14 in 1000 (14,000 in a million). Even the average level of radon in outdoor air, about 0.4 pCi/L, has a lifetime lung cancer risk of about 2 in 1000 (2000 in a million), according to the NJDEP.
Compare
that with the “acceptable” risk for a chemical carcinogen. The
Maximum Contaminant Level for benzene in drinking water is 5
parts per billion.
That's a risk of about 5 in a million, if you drink 2 liters a day
for 70 years.
The
NJDEP has a map of the NJ
coastal plain
that shows where higher radon levels are due to naturally-occurring
uranium deposits
usually found in glauconitic
soils.
One
in a Million
Here
are some other risks for getting cancer after being exposed to
radiation, based on the National
Academy of Sciences’ Report on the Biological Effects of Ionizing
Radiation (BEIR VII)
from 2006. The National
Research Council
posted a summary
of the BEIR VII report
that concluded that there is about a one-in-a-million risk of cancer
for each dose of 1 mrem.
This
does not include the dose from radon and other background radiation,
which is about half the average
exposure of 620 mrem a year in the US. It
is an average risk - it does not take into account the higher risk of
cancer in the younger years. Slide
18
shows the cancer risks at different ages after being exposed to
10,000 mrem (10 mGy),
based on BEIR VII.
Fracking
Waste and Nuclear Power Plants
North
Dakota is proposing to raise
the allowable level of radiation in fracking and other waste disposed
at their landfills. It would would increase the standard from 5
picocuries per gram
to 50 pCi/g. The state
Department of Health commissioned the Argonne
National Laboratory to determine how much a change in the
regulation would increase the exposure for workers and the public.
The ANL estimated that 50 pCi/g would increase the dose to no more
than 100 mrem a year.
The
Nuclear Regulatory
Commission requires nuclear power plants limit the public's
exposure to radiation to 100 mrem a year.
The average
risk of cancer determined in BEIR VII is about
a 1 in a million risk for each millirem. For 100 mrem, the risk
would be 100 in a million. The risk for being exposed to 100 mrem a
year would be 3000 in a million for 30 years, and 7000 in a million
for 70 years.
Protective
Action Guidelines for Disasters: Nuclear Power Plants, Dirty Bombs,
Nuclear Terrorism
In
2013, the EPA published its PAG
Manual Protective Action Guides And Planning Guidance For
Radiological Incidents. The “acceptable” levels in the PAGs
for disaster response, evacuation, and
remediation range from 100 to 2000 mrem a year.
The
advocacy group Nuclear
Resource and Information Service, using BEIR VII data - and
factoring the higher risk of cancer in the younger years - concluded:
“EPA's
estimate of a 70-year lifetime exposure at 2 rem per year [2000 mrem]
is that 1 in every 6 people exposed would get a cancer [166,667 in a
million] … Even at the 0.1 [100 mrem] lower end of possible cleanup
levels, the risk would be 1 cancer for every 123 people exposed
[8,130 in a million]. EPA historically has required cleanup
sufficient to prevent exposure to contaminants outside a risk range
of one in a million to one in ten thousand; these new recommendations
would permit risks orders of magnitude higher.”
The
highest PAG level, 2000 mrem (20
millisievert),
is being used to allow
residents to return to their homes contaminated by Fukushima
Daiichi. It is also what the NRC
proposed in 2014
as the highest annual dose for workers at nuclear facilities, down
from the current standard of 5000 mrem a year.
This
Blog Did Not
This
blog did not address the controversy
over predicting cancer rates from exposure to low level radiation:
“The
risk of increased cancer incidence is well established for doses
above 10 rem [10,000 mrem]. For low doses, it has not been possible
to scientifically determine if an increased risk exists, but many
scientists believe that small doses of radiation do lead to increased
cancer risk, and that the degree of risk is directly proportional to
the size of the dose. Risk estimates from low doses are obtained by
extrapolation from high dose observations.”
It
did not consider the trade-offs in those grim numbers in the 2013
PAGs for disaster response, evacuation, and remediation. According to
the EPA (on
page 76):
“Exposure
limits in a range of one in a population of ten thousand (10-4)
to one in a population of one million (10-6) excess
lifetime cancer incidence outcomes are generally considered
protective, though this may not be achievable after a large
radiological incident. In making decisions about cleanup goals and
strategies for a particular event, decision makers must balance the
desired level of exposure reduction with the extent of the measures
that would be necessary to achieve it, in order to maximize overall
human welfare.”
Or
as James
Conca, puts it, “You
personally might decide to become a refugee over rad levels
equivalent to living in Idaho, but do you have the right to make
someone else do that?”
The
lack of preparedness
for a radiological disaster outside the 10-mile
Emergency Planning Zones around Nuclear Power Plants is discussed
in this blog.
